Make LineWrappingAnsiTerminalWriter more efficient

...by only starting the new line, if needed and not already if the last
usable character of the line is written.

--
Change-Id: I86519389fe64fe74ba9045be07483ce5f55d5e9a
Reviewed-on: https://bazel-review.googlesource.com/#/c/3384
MOS_MIGRATED_REVID=119949042

1 files changed, 6 insertions, 3 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java b/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java
index 66c6d3b4c2..fa13fd6453 100644
--- a/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java
+++ b/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java
@@ -48,13 +48,16 @@ public class LineWrappingAnsiTerminalWriter implements AnsiTerminalWriter {
     if (c == '\n') {
       terminalWriter.newline();
       position = 0;
-    } else if (position + 2 < width) {
+    } else if (position + 1 < width) {
       terminalWriter.append(Character.toString(c));
       position++;
     } else {
-      terminalWriter.append(new String(new char[] {c, continuationCharacter}));
+      // The last usable character of the line was already been written,
+      // hence we have to start a continuation before writing the symbol.
+      terminalWriter.append(Character.toString(continuationCharacter));
       terminalWriter.newline();
-      position = 0;
+      terminalWriter.append(Character.toString(c));
+      position = 1;
     }
   }